The trend toward increasing the number of functions of an integrated circuit device (IC device) results in an increase circuit density in the device. With increased circuit density comes an increased processing power (i.e., increased data processing rate and clock speed) for the IC device. As the circuit density and processing power of the IC device increases, so does the amount of heat generated by the IC device. This can have detrimental effects as the reliability and performance of the IC device will decrease with an increase in the amount of heat the IC device is exposed to. It is important, therefore, to have an efficient heat dissipation system for the IC device.
There are a number of conventional methods of heat dissipation for IC devices including, active methods employing fans, refrigerants, or other recycled coolants, and passive methods such as heat sinks or heat spreaders.
FIG. 1 illustrates an IC device and associated packaging employing an integrated heat spreader IHS for heat dissipation in accordance with the prior art. The IC device and associated packaging 100, shown in FIG. 1, includes a substrate 101. IC device wafer 104 having a packaging 103 is coupled to substrate 101 using a plurality of solder bump connections 102. Typically the gap between solder bump connections 102 and the IC device packaging may be filled with an underfill material (e.g., epoxy), not shown. IHS 105 is thermally coupled to the IC device wafer 104. A thermal interface material, not shown, such as grease or gel may be applied between IC device wafer 104 and the IHS 105 to improve the heat transfer from the IC device to the IHS. Typically the IHS is constructed of a ceramic material or a metal such as aluminum or copper. Although aluminum is less expensive, copper has become the metal of choice for IHSs because of its superior heat transfer characteristics (the thermal conductivity of aluminum is 250 W/m·K, while the thermal conductivity of copper is 295 W/m·K).
Viable methods of providing heat dissipation in IC devices are becoming more and more complex because the conventional heat dissipation solutions are not effective for contemporary processing requirements. The effort continues to improve the heat dissipation of heat sinks by increasing the thermal conductivity of the material used. It is also possible to increase heat dissipation from device by decreasing the thickness of the IC device wafer. The wafer material, typically silicon, has a much lower thermal conductivity than copper. For example the thermal conductivity of silicon is approximately 120 W/m·K, while the thermal conductivity of copper is 295 W/m·K, as noted above. Therefore, if the thickness of the wafer can be reduced, the heat dissipation capacity of the IC device will be increased.
The IC device wafer, typically, approximately 775 microns, has a device layer that is typically less than 1 micron in thickness, so there is a substantial room to reduce the thickness of the IC device wafer. The reduced-thickness IC device wafer is then attached to the heat sink. Less silicon between the device layer and the heat sink increases the thermal conductivity, and hence the heat dissipation capacity, of the IC device heat dissipation system. Efforts have been made to reduce the thickness of the IC device wafer by polishing and/or grinding the wafer. However, these processes are time consuming and costly. Moreover, in substantially reducing the thickness, the IC device wafer is rendered difficult to handle and process due to how thin the wafer is thereby adding to the manufacturing cost and complexity.